In order to reduce power consumption of the passive or active matrix type organic EL display panel, it is usual to generate a reference current by a reference current generator circuit, which is operated with a source voltage of 3V to 5V, and distribute the reference currents correspondingly to respective terminal pins of the organic EL panel by a reference current distributor circuit. The reference currents distributed to the respective terminal pins are sent to D/A converters which are provided for the respective terminal pins as reference drive currents. The D/A converter circuit converts display data on the basis of the reference drive currents to generate analog drive currents corresponding to the display data, with which output current sources provided correspondingly to the respective terminal pins and operating with source voltage of 15V to 20V, are driven. Output currents of the output current sources are sent to the terminal pins of the organic EL panel as drive currents for driving organic EL elements provided correspondingly to the respective terminal pins. (Patent Reference 1)
For this reason, a drive circuit operating with a source voltage as low as 3V to 5V and a circuit operating with a source voltage as high as 15V to 20V, are provided in the current drive circuit. Therefore, a circuit, which operates with voltage covering these two source voltages, is required between these circuits. In Patent Reference 1, such circuit is realized by output side transistors of the D/A converter circuit constructed with a current mirror circuit. Therefore, an input side transistor of the current mirror circuit of the D/A converter operates with source voltage of 3V to 5V and the output side transistors operate with source voltage of 15V to 20V.    Patent Reference 1: JP-2003-308043A
In Patent Reference 1, a MOS transistor having high withstand voltage is used as the output side transistor of the current mirror circuit constituting the D/A converter circuit. Since a number of weighted output side transistors are provided for D/A conversion, the number of high withstand voltage transistors becomes very large, so that there is a problem that the area dedicated to the D/A converter circuit is increased.
In Japanese Patent Application No. 2004-95006 of the applicant of this application, a relatively high withstand voltage MOS transistor is connected between an input side transistor and an output side transistor of a current mirror circuit in series in order to solve the above problem.
By this invention, it is possible to use low withstand voltage transistor as the output side transistors of the current mirror circuit to thereby reduce the area dedicated to the output side transistors.
Incidentally, in order to drive the organic EL element, which is a capacitive load, by initially charging it, the drive current of the organic EL element becomes peak current in an initial stage of the driving. The peak current of the drive current is generated in a circuit upstream of the D/A converter circuit or in a circuit on downstream side of the D/A converter circuit. In JP-2003-234655A, a peak current generator circuit is provided between a D/A converter circuit and an output stage current source (Patent Reference 2). Further, in JP-2003-308043A, a peak current generator circuit is provided on an input side of a current mirror circuit of a D/A converter circuit (Patent Reference 3).    Patent Reference 2: JP-2003-234655A    Patent Reference 3: JP-2003-308043A